How many dominoes in a set?

All domino set contains all number pairs from doublt-zero to double-six with each number pair occuring exactly once. For example, the domino shown is two-four and also four-two. Hoe many dominoes in a set?



plz show the how you found the answer out.How many dominoes in a set?
The following is a quote from The Dictionary of Daily Wants (1859), describing English dominoes:



DOMINOES. – This game is played by two or four persons, with twenty-eight pieces of oblong ivory, plain at the back, but on the face divided by a black line in the middle, and indented with spots, from one to a double six, which pieces are a double-blank, ace-blank, double-ace, deuce-blank, deuce-ace, double-deuce, trois-blank, trois-ace, trois-deuce, double-trois, four-blank, four-ace, four-deuce, four-trois, double-four, five-blank, five-ace, five-deuce, five-trois, five-four, double-five, six-blank, six-ace, six-deuce, six-trois, six-four, six-five, and double-six. Sometimes a double set is played with, of which double twelve is the highest. At the commencement of the game, the dominoes are well mixed, with their faces downwards. Each person draws one, and if four play, those who choose the two highest are partners, against those who draw the two lowest; drawing the latter also serves to determine who is to lay down the first piece, which is reckoned a great advantage. Afterwards each player takes seven pieces at random. The eldest hand having laid down one, the next must pair him at either end of the piece he may choose, according to the number of pips or the blank in the compartment of the piece; but whenever any party cannot match the part, either of the domino last put down, or of that unpaired at the other end of the row, then he says “go,” and the next is at liberty to play. Thus they play alternately, either until one party has played all his pieces, and thereby won the game, or till the game be blocked; that is, when neither party can play by matching the pieces when unpaired at either end, then that party wins who possesses the smallest number of pips on the pieces remaining. In playing this game it is to the advantage of the player to dispossess himself as early as possible of the heavy pieces, such as a double-six, five, four, %26amp;c. Sometimes when two persons play, they take each only seven pieces, and agree to play or draw, that is when one cannot come in or pair the pieces on the board at the end unmatched, he then is to draw from the fourteen pieces in stock till he find one to suit.How many dominoes in a set?
28



0:0 - 0:6 = 7

1:1 - 1:6 = 6

2:2 - 2:6 = 5

3:3 - 3:6 = 4

4:4 - 4:6 = 3

5:5 - 5:6 = 2

6:6 - 6:6 = 1

7+6+5+4+3+2+1=28